1. Field of the Invention
The present invention relates to a black ink for inkjet recording, an ink cartridge, and an inkjet recording device.
2. Description of the Related Art
For a black ink for inkjet recording, carbon black is generally used as a colorant. The carbon black has a black color with slight other colors, so that the carbon black is not completely black color (i.e., achromatic color). Therefore, it has been known a means for obtaining an image having higher blackness by adding complementary colors to the slight other colors to thereby reducing saturation to that of the achromatic color.
For example, Japanese Patent (JP-B) No. 3859109 describes a black ink composition containing the carbon black in combination with a cyan pigment and a magenta pigment. A colorant of the complementary color may be a dye or a pigment, but is preferably the pigment from the viewpoint of lightfastness of the resultant image. However, use of a mixture of a plurality of the pigments makes it difficult to keep the pigments in their optimal dispersion states. Therefore, there is a problem that the pigments aggregate with each other over time, so that desired blackness cannot be achieved.